RGS9, a GTPase accelerator for phototransduction.
The rod outer segment phototransduction GAP (GTPase-accelerating protein) has been identified as RGS9, a member of the RGS family of G alpha GAPs. RGS9 mRNA expression is specific for photoreceptor cells, and RGS9 protein colocalizes with other phototransduction components to photoreceptor outer segment membranes. The RGS domain of RGS9 accelerates GTP hydrolysis by the visual G protein transducin (G alpha(t)), and this acceleration is enhanced by the gamma subunit of the phototransduction effector cGMP phosphodiesterase (PDEgamma). These unique properties of RGS9 match those of the rod outer segment GAP and implicate it as a key element in the recovery phase of visual transduction.
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Verna and Marrs McLean Department of Biochemistry, Baylor College of Medicine, Houston, Texas 77030, USA.
Cowan
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Wensel
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D000595:Amino Acid Sequence; D000818:Animals; D002417:Cattle; D018076:DNA, Complementary / Q000235:genetics; D020558:GTP Phosphohydrolases / Q000502:physiology*; D020690:GTPase-Activating Proteins; D008969:Molecular Sequence Data; D010786:Photoreceptor Cells / Q000378:metabolism; D011506:Proteins / Q000235:genetics / Q000378:metabolism / Q000502:physiology*; D012160:Retina / Q000378:metabolism; D012374:Rod Cell Outer Segment / Q000378:metabolism; D015293:Transducin / Q000502:physiology; D014785:Vision, Ocular / Q000502:physiology*
D018076:DNA, Complementary; D020690:GTPase-Activating Proteins; D011506:Proteins; D020558:GTP Phosphohydrolases; D015293:Transducin